In its early life, the Earth would have been peppered nearly continuously by asteroids smashing into our young planet. These fiery collisions made our world what it is today. It may seem like things have changed since then, given the vast assortment of life and wide blue oceans—and things have indeed changed. At least in some respects. However, Earth still receives thousands of tons of matter from space, but this is in the form of microscopic dust particles (as opposed to recurrent, energetic collisions).
Fortunately, in modern times, a large asteroid colliding with the surface of the Earth happens only very rarely. Nevertheless, it does happen from time to time.
As most are probably already aware, it is widely believed that an asteroid initiated the dinosaurs’ extinction some 65 million years ago. And more recently, the Russian Chelyabinsk meteor hit our planet in February of 2013. It entered at a shallow angle at 60 times the speed of sound. Upon contact with our atmosphere, it exploded in an air burst. The size of this body of rock (before it burned up and shattered) is estimated to be around 20 meters (across) and it weighed some 13,000 metric tons.